A message is carried towards a target receiver (T) at a known location by one or more mobile entities (L,Q) that receive and pass on the message by short-range communication. The message includes an indication of the location of the target receiver (T). Before a mobile entity (L,Q) is used to carry the message, a determination is made as to whether the direction of travel of the mobile entity concerned is generally towards either the target receiver (T) or an intermediate staging post suitable for progressing the message towards the target receiver.